Casting press plates



Agi! 23, 1940.

H. Fl HAGEMEYERA 2,198,497

cAsTING PnEss .PLATES Fmd'uays, 193e mi@ Wm@ E@ Q MW@ Dil El man@ TTF.3A.l I

INVENTOR HENKYf/fdwmx SATES PATENT ori-Alca CASTING PRESS PLATES HenryF. Hagemeyer, Chicago, lll., assigner to Castings Patent Corporation, acorporation of Illinois Application May 5, 1938, Serial No. 206,149

6 Claims.

My invention relates to casting presses, and more specifically topressure plates used in conjunction with a press for holding togetherthe cope and drag of a mold during the operation of pouring the moltenmetal into the mold.

In pouring a mold it is desirable to have the mold sections pressedtogether with suicient force to prevent the molten metal from escapingbetween the parting surfaces under the pressure exerted by the metal asit flows into the mold cavity. To enable better regulation and quickerapplication of pressure to A'the mold sections I prefer to use a fluidpressure cylinder, as illustrated in my copending application Serial No.207,932, filed May 14, 1938, for Casting mechanism, instead of weightsor clamps. My invention, however, is adapted for use with any of thesetypes of pressure means.

In preparing molds of the plastic or gypsum base type, it has been foundthat the mold material sets with more or less of a meniscus on its outeror exposed surface. When smooth, rigid, pressure plates have been used,therefore, it has been necessary to scrape or otherwise finish the backof each mold section to a plane surface in order to obtain uniformpressure over the entire area thereof, which is necessary to preventunequal or warping stresses in the mold tending to crack it, and toprevent excessive localized pressure between small areas of the partingsurfaces. Such smoothing of the mold section back'takes considerabletime which increases the expense of preparing the molds, and further islikely to result in breaking off corners or edges of the brit- 35 tledried mold.

I have found that the pressure of the pressing mechanism' may bedistributed substantially uniformly over the back of a mold having aslight concavity or meniscus by the use of a rigid plate havingrelatively sharp ridges or projections about its margin with ridges. orprojections of greater area on its central portion, or even with anunbroken central portion. It is-preferable, however, to have groovesthroughout the surface of the plate to permit escape of gas exudingthrough the mold, and I also prefer that all the projections be of thesame height.

My principal object, therefore, it to provide a pressure plate totransmit pressure from pressure creating meanssubstantially uniformlyover the surface of a mold having a slightly concave contact surface orone having a meniscus.

Another object is to provide such a plate which will be adapted for useon different molds having contact surfaces with more or less concavityor meniscus.

A further object is to provide a pressure transmitting plate which willnot interfere with and may expedite the'escape from the mold back of gasexuding through the mold body from. the cavity.

It is also desired to make such mechanism compact and durable, althougheconomical to construct and efllcient in use.

Other objects will be made clear in the following detailed descriptionof the preferred embodiment of my invention which is shown in theaccompanying drawing to illustrate the principles and operation of suchinvention. The novel features thereof are defined in the appendedclaims.

Fig. 1 is a plan View showing one half of the preferred form of mypressure plate, which is symmetrical about the center line shown, and

Fig. 1A is a plan view showing one half of a modified form of suchplate, als`o symmetrical about its indicated center line.

Fig. 2 is an end elevation of either the plate of Fig. 1 or that of Fig.1A.

vFig. 3 is a side elevation of the half plate of Fig. 1, and

Fig. 3A is a side elevation of the half plate of Fig. 1A.

Fig. 4 is a side elevation of the pressure plate and mold assembly,illustrating the use of plates such as shown in Figs. 1A and 3A.

Fig. 5 is a fragmentary perspective view of a portion ofthe plateillustrated inFigs. 1 and 3,-

and

Fig. 6 is a fragmentary end elevation with parts in section, showing theengagement of a pressure plate with a mold face.

As has been mentioned, the projections or ribs on the pressure platesserve two purposes, first that of providing intermediate grooves toconvey to the edge of the mold and plate assembly gases exuding fromvthe mold cavity through the body` thereof and escaping from the moldback, and second, to distribute the pressure substantially uniformlyover the mold sections and to avoid appreciable unequal stressingthereof when the mold back has a slight concavity or meniscus. Toaccomplish the first purpose it is not necessary that the projections beof non-uniform area, but to equalize the pressure distribution over theconcave mold back the marginal projections should beyof smaller areathan the central ones, to penetrate into the fillets a distancesuiiicient tok enable the central projections to engage the mold backrmly. As far as the second purpose is concerned, it will beappreciated-that the central portion might be unbroken by grooves.

A pressure plate designed for a. nearly square mold should be like thatindicated as I in Figs. 1 and 3, having two` sets of groovesl I0 and I Iwhich mutually intersect. The plate is preferably rectangular in shapeand one set of grooves consists of parallel grooves which mostconveniently are also arranged parallel to the longitudinal edges of theplate. Likewise, the cross grooves Il are preferably parallel to eachother and parallel also to the ends of the plate I, so that the groovesof the two sets intersect at right angles.

In the central portion of the plate may be projections in the form ofribs I2 which are defined by the respective grooves Ill. It will benoted that these grooves extend beyond the edge of the mold M restingthereon, as shown in Fig. 4, to be in free communication with theatmosphere when the plate is in pressing engagement with the mold.Preferably, these grooves extend clear to the edge of the plate I toform notches therein as shown in Fig. 2. The gases escaping from themold back will thus have a positive passage for their exit from betweenthe mold and the pressure plate. For still better ventilation, thegrooves Il may also extend clear to the edge of the plate to formnotches therein as shown in AFig. 3. Such provision is desirable wherethe meniscus is pronounced. As shown in Fig. 6, the meniscus tends toclog the grooves partially and the increase in the exit opening effectedby the cross grooves compensates for such clogging. If desired, thegrooves may be made progressively wider toward the edge of the plate toincrease the vent still further.

To obtain substantial uniformity of pressure over a mold surface havinga meniscus, the surface of a rigid pressure plate might be madecomplementally convex. Such an expedient is not entirely satisfactory,however, for the same plate must be used on' mold surfaces of widelyvarying degrees of concavity, and such a rigid plate could be madeaccurately complemental to a mold of only one degree and shape ofconcavity. Moreover, the machining of a plate surface -substantiallyplane in the center and having'a margin with a convexity progressivelyvarying in degree is a difficult task. I have therefore made theprojections, including the ribs or ridges I2 and the buttons I3 all ofthe same height, but have spaced the grooves nearer together at themargins than in the central portion of the plate. Thecentral'projections defined by such grooves are consequently of greaterwidth and area than thoseat the margins. As such a plate is forcedagainst the face of a mold the small marginal projections will beIcompelled to penetrate into the meniscus, as indicated in Fig. 6, untilthe central portion of the plate seats on the plane central portion ofthe mold back.

Over the central portion of the platethe ribs or projections should beof substantially 'the same two successive grooves nearer the center ofthe plate. Likewise, the Width of every projection or rib will be atleast-as great as that of every projection or rib disposed closer thanitself to the edge of the plate. Because more gas will ordinarily beliberated from the central portion of the mold surface, I prefer thatthe width of the central grooves be greater than that of the marginalgrooves.

Obviously, the number and widths of the projections, the number, widthsand depths of the' grooves, and the relative widths and depths of themarginal and central grooves and projections, as well as of the two setsof grooves and projections, may be varied considerably according to theaverage requirements of a particular installation. Precautions should betaken, however, to make the marginal projections sufliciently narrow sothat the. meniscus will be penetrated deeply enough to enable thecentral portion or projections'ofthe plate to come into firm pressingengagement with the mold without the marginal portions of the mold beingsubjectedto excessive pressure. In order to allow the marginalprojections to penetrate thus but still to exert finally substantiallytheir proportionate share of 'the pressure on the mold, I prefer that atleast the marginal projections be tapered from their bases to theirridges, so that as the penetration of yeach projection increases thepressure exerting area thereof also becomes progressively greater.

If the mold, instead of being nearly square, is relatively long andnarrow, the meniscus along the ends of the plate may be negligible. Forsuch cases the cross grooves Il may be omitted and the ribs I2 mayextend uninterruptedlyrfrom end to end of the plate, as shown in Figs.1A, 3A and 4. The notched formation of Fig. 2 will press into andperhaps serrate the slight meniscus at each end suiciently to enable thecentral portions of the ribs to come into contiguous engagement with themold back. The narrow ribs along the longer edges of the plate will, ofcourse, penetrate into the meniscus along each such edge as has beendescribed and as shown in Fig. 6.

While, for purposes of illustration, the construction of the lowerpressure plate has been shown in detail, the -upper pressure plate 2,pictured in Fig. 4, will b e provided with projections and grooves inthe same manner as plate I. An escape for pouring gases and substantialuniformlty of pressure will therefore be provided -for both upper andlower mold surfaces.

Escape of the air and pouring gases from the mold cavity through themold body may, if desired, be expedited by sealing the edges of thepressure plates and the groove ends, .and then evacuating the groovesthrough the body of each plate to increase the pressure differentialbetween the mold cavity and mold back. Such lowered pressure would alsoinduce ow of air into the edges of the porous mold and out the moldback, tending to cool the metal in the mold cavity, such cooling beinggreatest in the marginal portions of the mold and progressivelydecreasing toward the center, so that solidication, and cooling, andhence shrinkage, would occur in the order of first the castings from.their outer portions inward, then the gates, then the runners and nallythe sprue.

As my invention, I claim:

1,. A mold engaging pressure plate having on one face thereof moldengaging projections defined by intersecting sets of generally parallelgrooves, the spacing'between adjacent edges of successive adeuda? 'tothe plate edge than such rib, and the centrally grooves of each sei;` inthe central portion of the plate being greater than the spacing betweenadjacent edges of successive grooves of the same set near the margin ofthe plate.

2. A rectangular mold engaging pressure plate having on one face thereofmold. engaging projec tions dened by a set of parallel grooves disposedparallel to opposite edges of the plate and a second set of parallelgrooves disposed perpendicular to said first set of grooves and parallelto the other opposite edges o the plate, the spacing between adjacentedges of successive grooves of each set in the central portion of theplate being greater than the spacing between adjacent edges ofsuccessive grooves of each. set, respectively, disposed near the edge ofthe. plate.

3. A mold engaging pressure plate having on one face thereof coplanarmold engaging projections adapted to be in simultaneous engagement witha mold back, and defined by a plurality ofv successive grooves, thespacing between adjacent edges of successive grooves in the centralportion o the plate being greater than the spacing between adjacentedges of successive grooves near the edge of the plate.

4. A rectangular mold engaging pressure plate having on one face aplurality of parallel ribs disposed parallel to opposite plate edges,each rib being at least as wide as every rib disposed closer disposedribs being Wider than the ribs adjacent to the plate edge, and the spacebetween adjacent edges of adjacent centrally disposed ribs being greaterthan the space between adjacent edges of adjacent ribs near the plateedge.l

5. A mold engaging pressure plate having on its mold engaging face aplurality of mold engaging buttons of .small mold engaging surface areaspaced along the plate edges, and in the central portion of such face amold engaging projection of relatively large mold engaging surface areaas compared to that of such a button along the plate edge.

6. Al mold engaging pressure plate, having a planar mold engagingsurface including a cen= tral contact zone and a marginal contact noneadapt@ to be in simultaneous engagement with a mold baclr, both zones ofcontact being interrupted by depressions denning a plurality of narrowmold engaging surface portions in the marthe central lzone, adapted toabut the central portion of a mold back, thereby to distributesubstantially uniformly over the mold back the' e pressure plate.

i ist'

